The only alternative to expansion of agriculture is intensive cultivation. If we cannot expand our cropland, we shall have to make full use of our existing ones.
Mankind has so far been successful in producing more food than is actually needed by the exponentially rising human population if it is evenly distributed. Most of this enhanced productivity has come from intensive use of energy, chemical fertilizers, pesticides and high-yielding varieties which rapidly consume nutrients.
Man can raise food from sands as well. But the cost shall be heavy. The steep rise in food-grain production is a result of an equally steep rise in fertilizer use and energy expenditure. The world used about 14 million metric tons of fertilizer in 1950 to produce 624 million metric tons of food grains.
Now about 131 million metric tons of fertilizers are used to produce 1661 million metric tons of food grains. In other words, application of 1 metric ton of fertilizer gave about 45 metric tons of grains in 1950 A.D. The same amount of fertilizer application now produces about 12.5 metric tons of food grains.
Similarly energy application in the form of farm labour, tractor fuel, power for production of fertilizers, weeding, irrigation, harvesting and processing of grains etc. has gone up by seven to eight times. Total global consumption of energy for agriculture in 1950 A.D. was about 276 barrels of oil equivalent. By 1985 A.D. it rose to about 1903 million barrels of oil equivalent.
Why do we need an ever-rising amount of energy and chemical inputs to maintain fertility of crop fields? The answer is simple. Natural productivity and nutrient regeneration capacity of our soils have been ignored. The biotic community of the soil which recovers the nutrients, porosity, aeration and mixing of the soil is suppressed by intensive agriculture.
Nutrients which the soil microbes could regenerate automatically have to be supplied from outside sources. More energy is needed to irrigate and provide suitable conditions to the crop plants to grow. More chemicals are needed to protect the monoculture – the single variety or a species – from pathogens, insects and pests.